Internal combustion engines have contributed greatly to the advancement of society. Vehicles powered by these engines have shortened the travel times between us by making long distance road travel routine. Such engines, however, have also greatly contributed to the pollution of our environment. The combustion of petroleum products in these engines results in unwanted byproducts such as carbon monoxide, carbon dioxide, sulfur dioxide, nitrogen oxides, etc., that are exhausted into the atmosphere.
Vehicles powered by alternative energy sources are under development. One such alternative energy source is the fuel cell. Fuel cells generate electric power through, for example, reaction of hydrogen and oxygen. The electric power that is generated is used to drive an electric motor that, in turn, drives the wheels of the vehicle. The product of the chemical reaction in a fuel cell utilizing hydrogen and oxygen is water, a product which is essential to our environment and which is easily disposed of.
Regulation of the temperature of the fuel cell is an important consideration for fuel cell powered vehicles. For example, fuel cell performance (and sometimes, lifetime) depends on the temperature at which the fuel cell is operating. Without proper temperature regulation, the fuel cell stack may not be able to supply adequate power to the electric motor of the vehicle and, as such, may not deliver the performance levels that are demanded by the consuming public.
Merritt et al. U.S. Pat. No. 5,366,821 discloses a fuel cell system which includes a coolant circuit having an electrical coil heater to raise the fuel cell stack to operating temperature and maintain that temperature (see column 2, lines 25-30 and column 8, line 50-column 9, line 23).
Mizuno et al. U.S. Pat. No. 5,193,635 discloses several embodiments of a fuel cell powered wheeled vehicle.
Sanderson U.S. Pat. No. 3,507,702 discloses a compact fuel cell system which includes a coolant circuit having an electrical heater to raise the fuel cell stack to operating temperature and maintain that temperature (see column 6, lines 28-66).
Patent Abstracts Of Japan, vol. 16, no. 230 (JA 04-043568) discloses a fuel cell that allows stable control of the cooling water temperature, and promotes water heat recovery without substantial loss, by performing the proportional control of a flow control electric valve, or controlling the speed of a pump and a blower in a fuel cell cooling system.
PCT/International Publication No. WO 94/10716 (Application No. PCT/US93/10333) discloses solid polymer fuel cell systems with a conventional coolant subsystem extending through the fuel cell stack.